Four-stroke cycle internal combustion engine



Sept. 10, 1940. F. a. HALF'ORD 2,214,529

' FOUR-STROKE CYCLE INTERNAL COMBUSTION ENGINE Filed May 9, 1939 Fig.1.X,IX6 )f x? 62 Inventor Y TFB/ZnFa Q,

Patented Sept. 10, 1940 UNITED STATES rorm-s'moxr. crow INTERNALcoMBUs'noN ENGINE Frank Bernard Halford, Edgware, England, as-

signor to D. Napier & Son Limited, London, England, a company of GreatBritain Application May 9, 1939, Serial No. 272,693

In Great Britain May 11, 1938 v 13 Claims.

This invention relates to internal combustion engines operating on thefour-stroke cycle of the type comprising two parallel crankshafts gearedtogether so that they rotate at the same speed 5 and two rows or banksof cylinders disposed on diametrically opposite sides of each crankshaftwith their axes at right angles to the plane in which lie the axes ofrotation of the two crankshafts. For the sake of convenience suchengines will be hereinafter referred to as H-section engines", the banksof cylinders which lie parallel to one another on the same side of theplane containing the crankshaft axes will be referred to as adjacentbanks" and cylinders which lie in different banks but in the sametransverse plane at right angles to the axes of the crankshafts will bereferred to as corresponding cylinders.

The object of the invention is to provide an improved engine of theabove type in which the liability for synchronous torsionaloscillations, at least of the more violent character, to occur in thecrankshafts and transmission gearing within the normal speed range ofthe engine will be reduced or eliminated.

To this end, in an H-section internal combustion engine according to theinvention operating on the four-stroke cycle and having six cylinders ineach bank, the crankshafts are so. constructed and geared together thatthe piston in Y each cylinder in any bank reaches its top dead centre atthe same moment as the piston in the corresponding cylinder in theadjacent bank, the firing interval between corresponding cylinders inadjacent banks is 360 of crankshaft rotation two corresponding pistonsin the adjacent bank.

It is to be understood that the cylinders may be,

arranged horizontally, vertically or otherwise and that the term topdead centre refers to the point where a piston reaches the point nearestthe cylinder head irrespective of the direction in which the cylinderaxis extends.

The firing order to the cylinders in each bank is preferably that normalfor a six-cylinder inline engine. Thus, each crankshaft is preferably soconstructed that thepistons in cylinders I and Sin each bank movesynchronously, the pistons in cylinders 2 and in each bank movesynchronously and the pistons in cylinders 3 and 4 in each bank movesynchronously. In such an en ously with cylinder 5 in the adjacentbankand and each cylinder in a bank flres simultaneously engine thefiring order of the cylinders in each cylinder 3 in each bank firingsimultaneously with cylinder 4 in the adjacent bank.

Moreover, with such an engine the induction system may consist of twocentral feeder pipes each extending between two adjacent banks ofcylinders with a short connecting pipe from the central feeder to eachindividual cylinder. It will.

be seen that with this arrangement, since the firing interval betweencorresponding cylinders of adjacent banks is 360 of crankshaft rotation,such an arrangement results in even spacing of the induction impulses inthe short connecting pipes without any overlapping of the periods duringwhich mixture is being drawn respectively to two adjacent cylinders fromany one point in the length of the central feeder.

An exhaust system comprising two main exhaust pipes each extendingbetween two adjacent banks of cylinders with short connecting pipes fromthe main pipe to each individual cylinder may also be employed whetheran induction system of the above type is used or not, and will then havethe advantage that no two cylinders exhaust into the main pipesimultaneously at the same point in its length.

The invention may be carried into practice in various ways but oneconstruction according to the invention and a modification thereof areillustrated diagrammatically by way of example in the accompanyingdrawings, in which Figure 1 is a diagrammatic end elevation of oneconstruction of engine according to the invention,

Figure 2 is a side elevation showing the crankshafts and the gearingconnecting them in the engine shown in Figure 1, and

Figure 3 shows a modified. arrangement of gearing connecting thecrankshafts to one another and to two separate propeller shafts whichmay be adopted in an engine otherwise similar to that shown in Figures 1and 2. 4

In the construction illustrated in Figures 1 and 2 the engine comprisesfour rows of cylinders designated respectively by the reference lettersA, B, C and D all attached to a single crank case, indicated at E.Supported in bearings (not shown) in the crank case are two parallelcrankshafts X and Y which are geared together at one end by gear wheelsF, F meshing with a common gear wheel F mounted upon a'common drivenshaft F constituting, for example; a propeller shaft. It will thus beseen that the two crankbeing angularly coincident, the crank'throws x=and X being angularly coincident and the crank throws X and X beingangularly coincident, each pair of angularly coincident crank throwsbeing displaced by from the two other pairs of angularly coincidentcrank throws. The crankshaft Y is similarlyconstructed and arranged sothat the crank throws Y and Y are angularly coincident, the crank throwsY and Y are angularly coincident and the crank throws Y and Y areangularly coincident the cranks Y Y being connected by connecting rodsto.

pistons C and D in the cylinders l-6 of rows C and D. For the sake ofclearness, the positions of all six cranks on each crankshaft areindicated by the appropriate reference letters in Figure 1 although onlythree of such cranks are actually visible.

The cylinders in each bank will be referred to respectively by thenumbers I to 6 starting at the front cylinder and ending at the rearcylinder. It will thus be seen that for each bank of cylinders thepistons in cylinders I and 6 reach their top dead centre simultaneously,the pistons in cylinders 2 and 5 reach their top dead centresimultaneously and the pistons in cylinders 3 and 4 reach their top deadcentre simultaneously.

Further, as will be seen, the crankshafts are so geared together thateach piston in a cylinder in the bank A reaches its top dead centresimultaneously with the piston in the corresponding cylinder in theadjacent bank C while similarly each piston in a cylinder in the bank Breaches its top dead centre simultaneously with the piston in thecorresponding cylinder in the bank D.

The arrangement is such that the firing interval between thecorresponding cylinders in banks A and C is 360 of crankshaft rotation,that is to say half a complete working cycle, while similarly the firinginterval between the corresponding cylinders in banks B and D is 360 ofcrankshaft rotation. Thus, each; cylinder in bank A der in bank C whilesimilarly each cylinder in the bank B fires alternately with thecorresponding cylinder in the bank D but simultaneously with anothercylinder in the bank D.

Thus, cylinder l in bank A will fire simultaneously with cylinder 6 ofbank C, cylinder 2 of bank A will fire simultaneously with cylinder 5 ofbank C, cylinder 3 of bank A will fire simultaneously with cylinder 4 ofbank C, cylinder 4 of bank A will fire simultaneously with cylinder 3 ofbank C, cylinder 5 of bank A will fire simultaneously with cylinder 2 ofbank C and cylinder 6 of bank A will fire simultaneously with cylinder Iof bank C. The cylinders in banks B and D will fire in a similar mannerrelatively to one another.

The firing order of the cylinders in each bank may be any one of thepossible firing orders for a six-cylinder in-line four-stroke internalcombustion engine, the same firing order being; however, employed foreach of the separate banks of cylinders. The arrangement is preferablysuch, however, that the individual cylinders of each bank fire at equalintervals of 120 of crankshaft rotation, the firing order for each bankof cylinders being conventional firing order for a six-cylinder in-linefour-stroke cycle engine, namely the firing order l5-3-6--2--4 or Thusthe firing order and firing intervals of the various cylinders may beany one of those shown in the following table, the two crankshafts beingdesignated X and Y, the two rows of cylinders associated with crankshaftX being designated A and B while the two rows of cylinders associatedwith crankshaft Y are designated row C and row D as in the constructiondiagrammatically shown in Figures 1 and 2. The angles given are, it willbe understood, angles of crankshaft rotation measured from the top deadcentre position of the piston at the beginning of the firing stroke ofcylinder I in row A.

Bank 0 A 1 3 6 2 4 1 B 4 1 5 3 6 2 C 6 4 1 5 3 6 D 0 2 4 1 i. 5

fires alternately with the corresponding cylinder It will be understoodthat the firing order and 76 in bank C but simultaneously with anothercylinintervals may also be the reverse of any of those shown above. Thusthe reverse of the first example given in the above table would be asfollows:

as small variations in the torque delivered by the engine as ispossible. On the contrary, with an engine according to the presentinvention the Bank o 120 180 240 300 360 420 480 540 600 660 720 Eachadjacent pair of banks of cylinders has associated therewith aninduction system comprising a main induction pipe G connected by shortindividual connecting pipes G to the valvecontrolled inlet ports G2 ofthe cylinders in the .two adjacent banks. Similarly each pair ofadjacent banks of cylinders has associated therewith an exhaust systemcomprising a main exhaust pipe H connected by short individualconnecting pipes H to the valve-controlled exhaust ports H in thecylinders of the two adjacent banks.

It is to be understood that although poppet valves have beendiagrammatically shown, the arrangement is equally applicable to enginesemploying sleeve or other types of valve.

It will be seen that with such simple induction and exhaust systems inan engine according to the invention gas is not drawn into two cylinderssimultaneously from the same point in the length of either maininduction pipe nor does. exhaust gas enter the same point in the lengthof either main exhaust pipe simultaneously from any two cylinders. Thus,satisfactory distribution and exhaust characteristics tend to beobtained.

In the modified arrangement shown diagrammatically in Figure 3, whichmay be employed in an engine otherwise similar to that diagrammaticallyillustrated in Figure 1, the two crankshafts X and Y are connected bygearing comprising gear wheels J and J' connected respectively to thetwo crankshafts X and Y and meshing respectively with intermeshing gearwheels J and J The crankshaft X is connected by a further gear wheel Kto a gear wheel K secured to one propeller shaft K carrying a propeller,indicated at K, while the crankshaft Y carries a gear wheel L meshingwith a gear wheel L on a second hollow propeller shaft L carrying apropeller, indicated at L the propeller shaft L being coaxial with andsurrounding the propeller shaft K As will be seen the propeller shafts Land K rotate in opposite directions at the same speed as one another asdo the crankshafts. The pistons in the various cylinders, however, reachtheir top dead centres in the same sequence and at the same angles ofcrankshaft rotation as in the construction shown in Figures 1 and 2.Thus the firing order of each bank of cylinders and the cylinders whichfire simultaneously may in this construction also follow any one ofthose shown on the table given above.

It will be seen that with engines according to the invention there arealtogether six main torque impulses for each'revolution of thecrankshafts and that with the phasing of the two crankshafts and thefiring intervals chosen any two cylinders which fire simultaneously donot occupy the same transverse plane in the engine.

It will also be seen that the present invention departs from thegenerally recognized practice in multi-cylinder engines of so arrangingthe cylinders and cranks as to obtain the maximum number of torqueimpulses per revolution of the crankshaft or crankshafts and therebyobtain number of torque impulses per revolution is at the most half thatwhich could be obtained with the number of cylinders employed sincepairs of cylinders fire simultaneously.

The invention is, however, based on a complete analysis: of the forcestending to produce synchronous torsional oscillations in the crankshaftsand transmission apparatus and with an engine according to the presentinvention the occurrence of such synchronous torsional oscillations, atleast of the more violent character, tend to be eliminated, with theresult that an engine is obtained having very good characteristics fromthis point of view. Furthermore, by constructing each crankshaft in themanner normal for a six-cylinder in-line engine, smoothness of operationof each individual portion of the engine represented by a crankshaft anda bank of cylinders tends to be obtained.

Again, with an engine according to the invention in which, as generallypreferred and shown in Figures 1 and 2, thetwo crankshafts rotate in thesame direction, the fact that adjacent crank pins on the two crankshaftsrotate in synchronism enables the distance between the axes of thecrankshafts to be small with consequent improvement in the compactnessof the engine. Again, the invention enables a simple induction system ora simple exhaust system such as those referred to above or both suchsimple systems tend to be obtained. Again, when the two crankshafts areconnected to a common transmission shaft by separate gear wheels ortrains of gear wheels meshing with different points in-the cir-,

cumference of a common gear wheel on the transmission shaft, the effectof the simultaneous firing in two banks of cylinders is to producesimultaneous substantially equal torque impulses on each crankshaft andthus tend to balance the power transmitted to the transmission shaftgear wheel respectively through the separate gear wheels or trains ofgear wheels, whereby the transmission shaft gear wheel is maintainedapproximately in a state of pure torsion and is not subjected toanyappreciable lateral thrusts or bending stresses due to ,difierences inthe tooth loads on the gear wheels meshing respectively with theopposite sides thereof.

It is to be understood that the construction more particularly describedabove is given by way of example only and that modifications may be madetherein without departing from this invention.

What I claim as my invention and desire to secure by Letters Patent is:I

1. A four-stroke cycle internal combustion engine including incombination two similar parallel crankshafts each having cranks l and 6angularly coincident, cranks 2 and 5 angularly coincident and cranks 3and 4 angularly coincident' two banks of cylinders each containing sixcylinders disposed on diametrically opposite sides of each crankshaftwith their axes at right angles to the plane in which lie the axes ofrotation of the two crankshafts, pistons in the cylinders, each crank ofeach crankshaft being connected to the two pistons in correspondingcylinders of the two banks disposed on opposite sides of that crankshaftgearing connecting the crankshafts so that they rotate at the same.speed and each piston in a bank reaches its top dead centre at the samemoment as the corresponding piston in the adjacent bank, the firinginterval between corresponding cylinders in adjacent banks being 360 ofcrankshaft rotation and each cylinder in a bank firing simultaneouslywith a cylinder in the adjacent bank.

2. A. four-stroke cycle internal combustion engine including incombination two similar parallel crankshafts each having cranks l and 6angularly coincident, cranks 2 and 5 angularly coincident and cranks 3and 4 angularly coincident, two banks of cylinders each containing sixcy1- inders disposed on diametrically opposite sides of each crankshaftwith their axes at right angles to the plane in which lie the axes ofrotation of the two crankshafts, gearing connecting the crankshafts sothat they rotate at the same speed and each piston in a bank reaches itstop dead centre at the same moment as the corresponding piston in theadjacent bank, the firing interval between corresponding cylinders inadjacent banks being 360 of crankshaft rotation and each cylinder in abank firing simultaneously with a cylinder in the adjacent bank, thefiring order of the cylinders in each bank being .-l53-6-24, cylinder iin each bank firing simultaneously with cylinder 6 in the adjacent bank,cylinder 2 in each bank firing simultaneously with cylinder 5 in theadjacent bank and cylinder 3 in each bank firing simultaneously withcylinder 4 in the adjacent bank.

3. A four-stroke cycle internal combustion engine including incombination two similar parallel crankshafts'each having cranks l and 6angularly coincident, cranks 2 and 5 angularly coincident and cranks 3and l angularly coincident, two banks of cylinders each containing sixcylinders disposed on diametrically opposite sides of each crankshaftwith their axes at right angles to the plane in which lie the axes ofrotation of the two crankshafts, gearing connecting the crankshafts sothat they rotate at the same speed and each piston in a bank reaches itstop dead centre at the same moment as the corresponding piston in theadjacent bank, the firing interval between corresponding cylinders inadjacent banks being 360 of crankshaft rotation and each cylinder in abank firing simultaneously with a cylinder in the adjacent bank, thefiring order of the cylinders in each bank being l-4 2--G 3-5, cylinderl in each bank firing simultaneously with cylinder 6 in the adjacentbank, cylinder 2 in each bank firing simultaneously with cylinder 5 inthe adjacent bank and cylinder 3 in each bank firing simultaneously withcylinder 5 in the adjacent bank.

4. A four-stroke cycle internal combustion engine including incombination two similar parallel crankshafts each having cranks i and 6angularly coincident, cranks 2 and 5 angularly coincident and cranks 3and & angularly coin-- cident, two banks of cylinders each containingsix cylinders disposed on diametrically opposite sides of eachcrankshaft with their axes at right angles to the plane in which lie theaxes of rotation of the two crankshafts, pistons in the cylinders, eachcrank of each crankshaft being connected to the two pistons incorresponding cylinders of the two banks disposed on opposite sides ofthat crankshaft gearing connecting the crankshafts so that they rotateat the same speed and in the same direction and each piston in a bankreaches its top dead centre at the same moment as the correspondingpiston in the adjacent bank, the firing interval between correspondingcylinders in adjacent banks being 360 of crankshaft rotation and eachcylinder in a bank firing simultaneously with a cylinder in the adjacentbank.

5. A four-stroke cycle internal combustion engine including incombination two similar parallel crankshafts each having cranks I and 6angularly coincident, cranks 2 and 5 angularly coincident and cranks 3and 4 angularly coincident, two banks of cylinders each containing sixcylinders disposed on diametrically opposite sides of each crankshaftwith their axes at right angles to the plane in which lie the axes ofrotation of the two crankshafts, gearing connecting the crankshafts sothat they rotate at the same speed and in the same direction and eachpiston in a bank reaches its top dead centre at the same moment as thecorresponding piston in the adjacent bank, the firing interval betweencorresponding cylinders in adjacent banks being 360 of crankshaftrotation and each cylinder in a bank firing simultaneously with acylinder in the adjacent bank, the firing order of the cylinders in eachbank being l-5-3-6 24, cylinder l in each bank firing simultaneouslywith cylinder 6 in the adjacent bank, cylinder 2 in each bank firingsimultaneously with cylinder 5 in the adjacent bank and cylinder 3 ineach bank firing simultaneously with cylinder 4 in the adjacent bank.

6. A four-stroke cycle internal combustion engine including incombination two similar parallel crankshafts each having cranks i and 6angularly coincident, cranks- 2 and 5 angularly coincident and cranks 3and 4 angularly coincident, two banks of cylinders each containing sixcylinders. disposed on diametrically opposite sides of each crankshaftwith their axes at right angles to the plane in which lie the axes ofrotation of the two crankshafts, gearing connecting the crankshafts sothat they rotate at the same speed and in the same direction and eachpiston in a bank reaches its top dead centre at the same moment as thecorresponding piston in the adjacent bank, the firing interval betweencorresponding cylinders in adjacent banks being 360 of crankshaftrotation and each cylinder in a bank firing simultaneously with acylinder in the adjacent bank, the firing order of the cylinders in eachbank being l42- 6-3-5, cylinder l in each bank firing simultaneouslywith cylinder 6 in the adjacent bank, cylinder 2 ineach bank firingsimultaneously with cylinder 5 in the adjacent bank and cylinder 3 ineach bank firing simultaneously with cylinder 4 in the adjacent bank.

7. A four-stroke cycle internal combustion engine including incombination two similar paralsame crankshaft, two banks of cylinderseach containing six cylinders disposed on diametrically opposite sidesof each crankshaft with their axes at right angles to the plane in whichlie the axes of rotation of the two crankshafts, pistons in thecylinders, each crank of each crankshaft being connected to the twopistons in corresponding cylinders of the two'banks disposed on oppositesides of that necting the crankshafts so that they rotate at the samespeed and each piston in a bank reaches its top dead centre at the samemoment as the corresponding piston in the adjacent bank, the firinginterval between corresponding cylinders in adjacent banks being 360tion and each cylinder in a bank firing simultaneously with a cylinderin the adjacent bank, and two propeller shafts driven respectively fromthe two crankshafts.

8. A four-stroke cycle internal. combustion engine including incombination two similar parallel crankshafts eachcrank of each of whichis angularly coincident with another crank of the same crankshaft, twobanks of cylinders each containing six cylinders disposed ondiametrically opposite sides of each crankshaft with their axes at rightangles to the plane in which lie the axes of rotation of the twocrankshafts, gearing connecting the crankshafts so that they r0- tate atthe same speed and each piston in a bank reaches its top dead centre atthe same moment as the corresponding piston in the adjacent bank, thefiring interval between corresponding cylinders in adjacent banks being360 of crankshaft rotation and each-cylinder in a bank firing si--multaneously with a cylinder in the adjacent bank, two main inductionpipes each extending between two adjacent banks of cylinders, and ashort connecting pipe extending from each individual cylinder to theadjacent main induction pipe.

9. A four-stroke cycle internal combustion engine including incombination two similar parallel crankshafts each having cranks I and 6angularly coincident, cranks 2 and 5 angularly coincident and cranks 3and 4 angularly coincident, two banks of cylinders each containing sixcylinders disposed on diametrically opposite sides of each crankshaftwith their axes at right angles to the plane in which lie the axes ofrotation of the two crankshafts, gearing connecting the crankshafts sothat they rotate at the same speed and each piston in a bank reaches itstop dead centre at the same moment as the corresponding piston in theadjacent bank, the firing interval between corresponding cylinders inadjacent banks being 360 of crankshaft rotation and each cylinder in abank firing simultaneously with a cylinder in the adjacent bank, twomain induction pipes each extending between two adjacent banks ofcylinders, and a short connecting pipe extending from each individualcylinder to the adjacent main induction pipe.

10. A four-stroke cycle internal combustion engine including incombination two similar parallel crankshafts each crank of each of whichI is angularly coincident with another crank of the same crankshaft, twobanks of cylinders each containing six cylinders disposed ondiametrically opposite sides of axes at right angles to the plane inwhich lie the axes of rotation of the two crankshafts, gearingconnecting the crankshafts so that they rotate at the same speed andeach piston ina bank crankshaft gearing conof crankshaft rotacoincidentand cranks cylinders disposed on each crankshaft with their reaches itstop dead centre at the same moment as the corresponding piston in theadjacent bank, the firing interval between corresponding cylinders inadjacent banks being 360 of crankshaft rotation and each cylinder in abank firing simulthe adjacent bank,

taneously with a cylinder in two main exhaust pipes each extendingbetween two adjacent banks of cylinders and a short connecting pi econnecting each cylinder to the adjacent main exhaust pipe.

'11. A four-stroke cycle internal combustion engine including incombination two similar parallel crankshafts each having cranks l and 6angularly coincident, cranks 2 and 5 angularly 3 and 4 angularlycoincident, two banks of cylinders each containing six cylindersdisposed on diametrically opposite sides of each crankshaft with theiraxes at right angles to the plane in which lie the axes of rotation ofthe two crankshafts, gearing connecting the crankshafts so that theyrotate at the same speed and each piston in a bank reaches its top deadcentre at the same moment as the corresponding piston in the adjacentbank, the firing interval between corresponding cylinders in adjacentbanks being 360 of crankshaft rotation and each cylinder in a bankfiring simultaneously with a cylinder in the adjacent bank, two mainexhaust pipes each extending between two adjacent banks of cylinders anda short connecting pipe connecting each cylinder to the adjacent mainexhaust pipe.

12. A four-stroke cycle internal combustion engine including incombinationtwo similar parallel crankshafts each crank of each of whichis angularly coincident with another crank of.

the same crankshaft, two banks of cylinders each containing sixcylinders disposed on diametrical- 1y opposite sides of each crankshaftwith their axes at right angles to the plane in which lie the axes ofrotation of the'two crankshafts, gearing connecting the crankshafts sothat they rotate at the same speed and each piston in a bank reaches itstop dead centre at the same moment as the corresponding piston in theadjacent bank, the firing interval between corresponding cylinders inadjacent banks being 360 of crankshaft rotation and each cylinder in abank firing simultaneously with a cylinder in the adjacent bank, twomain induction pipes each extending between two adjacent banks ofcylinders, a short connecting pipe extending from each individualcylinder to the adjacent main induction pipe, two main exhaust pipeseach extending between two adjacent banks of cylinders, and a shortconnecting pipe connecting each cylinder to the adjacent 'main exhaustpipe. v

13 A four-stroke cycle internal combustion engine including incombination two similar parallel crankshafts each having cranks I and 6angularly coincident, cranks 2 and 5 angularly coincident and cranks 3and 4 angularly coincident, two banks of cylinders each containing sixdiametrically opposite sides of each crankshaft with their axes at rightangles to the plane in which lie the axes of rotation of the twocrankshafts, gearing connecting the crankshafts so that they rotate atthe same speed and each piston in a bank reaches its top dead centre atthe same moment as the corressponding piston in the adjacent bank, thefiring interval between corresponding cylinders in adjacent banks being360 of crankshaft rotation and each cylinder in a. bank firingsimultaneous- 1y with a cylinder in the adjacent bank, two maininduction pipes each extending between two adjacent banks of cylinders,a. short connecting pipe extending from each individual cylinder to theadjacent main induction pipe, two main exhaust pipes each extendingbetween two adjacent banks of cylinders and a short connecting pipeconnecting each cylinder to the adjacent main exhaust pipe.

FRANK BERNARD HALFORD.

